PURPOSE: To separate and recover Ni, Co, copper at a high yield from manganese nodule by dissolving the manganese nodules in acid. adding a rubeanic acid to separate Ni, Co, copper, performing adsorption, elution process by making the use of iron exchange resin.

CONSTITUTION: The manganese nodules are dissolved in hydrochloric acid or the like and the insoluble contents are filtered away. The solution is then controlled to around pH 6, to which a rubeanic acid solution is added and the solution is heated to 60 to 70°C to allow Ni, Co, copper to precipitate, thence the greater part of Mn and iron is removed. This precipitate is dissolved in a concentrated nitric acid or the like and is evaporated to dryness, after which it is dissolved in a dilute bydrochloric acid and the solution is next passed through a cation exchange resin column to allow the remaining iron and Al to be adsorbed and removed. next, the solution is passed through an anion exchange resin column to let the metal components be adsorbed. Following to this, Ni is eluted by a hydrochloric acid of 0.5 to 10.5 normality and Co and copper are eluted by a hydrochloric acid of 3.5 to 4.5 normality.